Working machines include portable working machines that can freely be transferred to a field site, and some kinds of such portable working machines have a working unit driven by a gaseous-fueled engine (hereinafter-referred to, for brevity, as “gas engine”). One example of such working unit is a combined gas-engine generator unit disclosed, for example, in Japanese Patent Laid-Open Publication (JP-A) No. 2006-97584.
The disclosed combined gas-engine generator unit includes a gas engine drivable by a fuel supplied from a gas cartridge, a generator driven by the gas engine, and a controller for controlling the gas engine and the generator. The gas cartridge, the gas engine, the generator and the controller are housed in a portable container or case. In use, the combined gas-engine generator unit is place on a floor and operated so that the generator is driven by the gas engine to generate electric power that can be supplied to an external appliance.
The gas engine has a lubricating system which in many cases employs a so-called “oil sump system” in which a lubricating oil held in a crankcase is distributed to sliding parts of the engine. The portable combined gas-engine generator unit is simply placed on the floor without anchoring, and hence, it may occur that the combined gas-engine generator unit falls down due to some reasons depending on installation conditions. If such falling occurs during operation of the combined gas-engine generator unit, it is desirable to stop the combine gas-engine generator unit immediately. The same situation applies to other types of portable working machines.